An efficient screening procedure detecting six novel mutations in the LDL receptor gene in Swedish children with hypercholesterolemia

Abstract

Familial hypercholesterolemia (FH) is an autosomal semi-dominant disorder caused by defects in the low density lipoprotein receptor (LDLR) gene and is a well-documented risk factor for developing cardiovascular disease. The LDLR genes of five Swedish children with FH were examined in this study. Initial mutation screening was performed by denaturing gradient gel electrophoresis (DGGE) with enzymatically amplified exon-sized fragments, each containing a tailing GC-rich requence. The GC-clamped fragments had been synthesized with a restriction site adjacent to the intron-corresponding sequence to allow detachment of the clamps, thereby rendering the fragments suitable for subsequent analysis by single-strand conformation polymorphism (SSCP) analysis of samples from patients with no DGGE-detectable mutations. In addition, all the LDLR genes of the patients were screened for large alterations by restriction fragment length polymorphism analysis. Following this strategy, seven different, potentially disease-causing mutations were detected in the five children with FH. Six of the alterations, five single-base substitutions and one dinucleotide deletion, have not previously been described. DGGE detected six of the mutations and SSCP the seventh.

Splice-Site Mutations in Atherosclerosis Candidate Genes

“…Phenotypic analyses were limited to patients with fasting plasma lipid and homocysteine levels. Because outlier phenotypes were derived using stringent statistical criteria, some patients originally described as severely or mildly affected were categorized as having ‡Genotype of mutation designated as homozygous (11), heterozygous (12), or compound heterozygous (23). §Protein activity and mass are, respectively, the percent normal enzymatic activity/binding and the level of expression.…”

Sequence Diversity in Genes of Lipid Metabolism

“…Three of these mutations were in LDLR, and of these mutations, one was previously known (Hobbs et al 1989). The second LDLR mutation was identified in a 41-year-old Caucasian man whose plasma cholesterol level was extremely responsive to changes in dietary cholesterol content; the mutation had been identified previously in a patient with classic FH (Ekstrom et al 1995), but was not associated with defective LDLR function in cultured fibroblasts (Ekstrom et a. 2000).…”

The importance of an integrated analysis of clinical, molecular, and functional data for the genetic diagnosis of familial hypercholesterolemia

“…23,[27][28][29] Biochemical characteristics of each mutation carrier are shown in Supplementary Table S1 online. Only data for adults without treatment were included (except lipoprotein(a)) because no values were registered for the majority of pediatric patients.…”